1. Field of the Invention
The present invention relates to a rolled plate joining apparatus for joining the tailing end of a preceding rolled plate and the leading end of a succeeding rolled plate while traveling with the rolled plates in a hot rolling plant and to a continuous hot rolling apparatus equipped with the same.
2. Description of the Related Art
In conventional hot rolling plants (hot strip mills), bar materials rolled by a roughing mill are supplied separately to a finishing mill to obtain strip materials having a desired thickness. By such a means, however, all the rolled plates are not rolled uniformly, and, therefore, such problems as defects of leading ends and tailing ends are liable to occur, thereby lowering the yield of the rolled plates; and it is hard to increase the rolling speed due to such defects.
To solve the above problems, there are conventionally suggested joining apparatuses for joining the tailing end of a preceding rolled plate and the leading end of a succeeding rolled plate so as to supply the rolled plates to a finishing mill successively (e.g., Japanese Unexamined Patent Publication Nos. 62-252603 and 63-93408 and Japanese Patent Publication No. 5-139).
In the above-described rolled plate joining apparatuses, however, there are such problems as (1) the automation (mechanization) is difficult and the joined sections cannot be rolled uniformly, (2) since it takes long time to weld wide rolled plates, the overall length of the plant is apt to be long, and (3) it is difficult to secure a satisfactory joined strength throughout the width of the rolled plates.
Therefore, the inventors of the present invention thought out a rolled plate joining apparatus capable of joining rolled plates with a satisfactory joined strength throughout the width in a short period of time and filed applications thereon (e.g., Japanese Unexamined Patent Publication No. 8-10809).
FIG. 1 is an example of a rolled plate joining apparatus made by the inventors of the present invention.
This rolled plate joining apparatus is equipped with a truck 3 that travels in the rolling direction, tailing end pinch rolls 4 that are mounted on the truck 3 and can be moved vertically with the tailing end of a preceding rolled plate 1 pinched horizontally, leading end pinch rolls 5 that are mounted on the truck 3 and can pinch horizontally the leading end of a succeeding rolled plate 2, machining apparatuses 6 for cutting the undersurface of the tailing end of the preceding rolled plate 1 and the upper surface of the leading end of the succeeding rolled plate 2, and a pressure welding apparatus 7 for joining the preceding rolled plate 1 and the succeeding rolled plate 2 with the machined surfaces of the preceding rolled plate 1 and the succeeding rolled plate 2 overlapped and reduced approximately to the thickness of the rolled plates 1 and 2.
Further, as is shown in FIGS. 2a and 2b, the rolled plate joining apparatus of Japanese Unexamined Patent Publication No. 8-10809 is equipped with the truck 3 that travels with apparatuses mounted thereon, a tailing end clamping apparatus 9 that can be moved vertically between a machining level H and a pressure welding level L by an elevating apparatus 8 with the tailing end of the preceding rolled plate pinched horizontally, a leading end clamping apparatus 10 for pinching and holding the leading end of the succeeding rolled plate 2 at a pressure welding level L, a machining apparatus 11 for cutting simultaneously the undersurface of the tailing end of the preceding rolled plate 1 and the upper surface of the leading end of the succeeding rolled plate 2, a reduction keeping apparatus 12a for keeping the surfaces to be cut in a reducing atmosphere, and a pressure-welding apparatus 12b for pressure-welding the overlapped sections.
The machining apparatus 11 is composed of a conical cutter 13 that is rotated about an axis X slanted to the level and a traverse moving apparatus 14 for moving horizontally the conical cutter 13 throughout the width of the rolled plates from a position that is out of the position of the rolled plates. The conical cutter 13 has a pair of truncated conical surfaces 13a, 13b whose tops are directed outward and the uppermost part and the lowermost part of the truncated conical surfaces are generally horizontal, so that the uppermost part and the lowermost part of the truncated conical surfaces can touch the undersurface of the tailing end and the upper surface of the leading end simultaneously respectively. In passing, cutter tips 13c are embedded in the truncated conical surfaces 13a, 13b. Further, 15a indicates a traverse moving table of the traversing apparatus 14.
Further, Japanese Unexamined Patent Publication No. 7-214104 describes a hot rolling plant wherein joining machine is used. As is shown in FIG. 3 of the present application, this hot rolling plant is provided with a sizing press 16b on the exit side of a heating furnace 16a, and the leading end and the tailing end of a rolled plate 1 rolled by a roughing mill 16c provided on the exit side thereof is sheared by a crop shear 16d. The tailing end of the sheared preceding sheet bar and the leading end of the sheared succeeding sheet bar are joined by a fuse-joining apparatus 17 and are subjected to finish rolling by a group of finishing mills 16e and the joined sheet bars are wound by a winding machine 16f. 
(1) In the rolled plate joining apparatus shown in FIG. 1 or 2 of the present application, it is required to align the center lines of the preceding rolled plate 1 and the succeeding rolled plate 2. FIG. 4 shows a state wherein the center line of one rolled plate is not aligned with the center line of other rolled plate to be joined and if they are joined in this state, plate breaking or camber due to the defective joining will occur. FIG. 5 of this application shows misalignment of the center lines in the joined sections of rolled plates having different widths. If the center line of a preceding rolled plate and the center line of a succeeding rolled plate are misaligned in this way, problems arise that will cause serious troubles with succeeding finishing rolling or the like.
(2) Further, the life of the conical cutter 13 of the rolled plate joining apparatus shown in FIG. 2 of the present application is extremely short due to such factors as [1] the conical cutter 13 is exposed to a high-temperature atmosphere by the reduction keeping apparatus, [2] the conical cutter 13 is rotated at a high speed by the driving apparatus, [3] the conical cutter 13 is moved horizontally in the width direction of the rolled plates by the traverse moving apparatus, and [4] use of the cutter tips for the conical cutter makes the heat capacity small. In addition, it is difficult to provide a cooling mechanism, because, for example, [1] the driving apparatus is attached to the extremity of the shaft of the conical cutter and [2] a key groove into which a key is fitted is formed in the inner circumferential surface of the conical cutter.
(3) Furthermore, in the rolled plate joining apparatus, the cutting of the surfaces to be joined is required to be done in a short period of time. Because, if the cutting time becomes long, the joining time becomes long, which makes the traveling distance of the joining apparatus long and therefore the rolling line becomes long. Furthermore, since the surfaces to be cut during the cutting are covered with reducing flames to prevent them from being oxidized, the surfaces to be cut are at a high temperature and therefore a lubricant cannot be used during the cutting. As a result, the cutter tips are abraded intensely, the life thereof is short, and therefore the cutter has to be replaced frequently. Further, if the cutter is damaged during the cutting, the replacement takes a longer time, and during that time, the joining operation and the rolling operation have to be stopped. The joining is carried out with a certain interval between the joining operations, but the heat capacity of the cutter is large, the cutter tips are not cooled in many cases until the next joining operation, and therefore the temperature of the cutter tips during the cutting is increased to make the life short.
(4) Furthermore, in the hot rolling plant shown in FIG. 3 of the present application, since the rolled plates after the rough rolling are not wound, the rolling line becomes long. Then, in this plant, the temperature of the rolled plates supplied to the finish rolling machine is lowered and the finish rolling cannot be carried out suitably in many cases. Furthermore, in many cases, the joined sections bulge in the plate width direction, and this bulge is expanded by rolling in the succeeding step. FIG. 6 herein shows the shape of the bulge at the joined sections. The plate width at the joined position of the rolled plate 1 has a bulge 1a. In FIG. 7 of this application, the rolled plate 1 is tapered at the opposite ends to form edge drops 1b. Edge drops 1b cannot secure the precision of the plate thickness at the opposite ends and therefore are trimmed, resulting in a decrease in the yield. The plant shown in FIG. 3 does not have a correcting apparatus for correcting such joined sections or a defective thickness at the opposite ends due to rolling. Furthermore, since there is no shear before the winding machine, it is required to sever the rolled plates for every quantity of the rolled plates that can be wound by the winding machine and the ability capable of operating continuously by the joining machine is not used. In passing, Japanese Unexamined Patent Publication No. 7-24503 discloses a post-forming machine for removing defective parts due to joining positioned on the exit side of a joining machine, but this post-forming machine cannot correct edge drops resulting from finish rolling.
The present invention has been thought out so as to solve the above-described various problems. That is, a first object of the present invention is to provide a rolled plate joining apparatus that has a sensing apparatus for aligning the center lines of a preceding rolled plate and a succeeding rolled plate.
Further, a second object of the present invention is to provide a rolled plate joining apparatus that has cutter cooling apparatuses capable of efficiently cooling conical cutters, and particularly cutter tips.
Still, a third object of the present invention is to provide a rolled plate joining apparatus that allows a waiting cutter to be cooled rapidly, allows an abrasion preventive agent to be applied to a waiting cutter, and allows a cutter be replaced rapidly.
Further, a fourth object of the present invention is to provide a continuous hot rolling apparatus that shortens a rolling line, improves the productivity of strip materials by continuous rolling and the preciseness of the width and thickness of plates, and increases the ability of adjusting the width of slabs to decrease the types of the widths of slabs on the side of a continuous casting machine to which the slabs are supplied to improve the productivity.
To attain the first object, according to the present invention, there is provided a rolled plate joining apparatus equipped with a truck that can travel reversibly in the rolling direction, tailing end pinch rolls that are mounted on said truck and can be moved vertically with the tailing end of a preceding rolled plate pinched horizontally, leading end pinch rolls that are mounted on said truck and can pinch horizontally the leading end of a succeeding rolled plate, machining apparatuses for cutting one surface of the tailing end of the preceding rolled plate and the other surface of the leading end of the succeeding rolled plate, and a pressure welding apparatus for compressing the preceding rolled plate and the succeeding rolled plate with the machined surfaces overlapped to reduce them approximately to the thickness of the rolled plates, comprising a tailing end centering apparatus placed between said tailing end pinch rolls and said pressure welding apparatus for pressing the opposite width ends of the tailing end of the rolled plate to align the center line of said rolled plate with the center line of said joining apparatus in the rolling direction and a leading end centering apparatus placed between said pressure welding apparatus and said leading end pinch rolls for pressing the opposite width ends of the leading end of the rolled plate to align the center line of said rolled plate with the center line of said joining apparatus in the rolling direction.
By the above constitution, the tailing end centering apparatus aligns the center line of a preceding rolled plate with the center line of the joining apparatus in the rolling direction at the tailing end of the preceding rolled plate. Herein the term xe2x80x9cthe center line of the joining apparatus in the rolling directionxe2x80x9d means the line along which the center line of the rolled plate is to be passed and is generally the center line of the joining apparatus in the rolling direction but also includes lines parallel to it. Further, the leading end centering apparatus aligns the center line of a succeeding rolled plate with the center line of the joining apparatus in the rolling direction at the leading end of the succeeding rolled plate. Thus, the pressure welding can be made with the center line of a preceding rolled plate aligned with the center line of a succeeding rolled plate.
In accordance with a preferred embodiment of the present invention, each of said tailing end centering apparatus and said leading end centering apparatus comprises guide plates provided along the opposite width ends of the rolled plate, a lower rack plate having a rack on the upper surface in the plate width direction and fixed to one of the guide plates, an upper rack plate having a rack on one surface in the plate width direction and fixed to the other of the guide plates, a pinion arranged between said lower rack plate and said upper rack plate and meshed with said racks of said rack plates, and a rack plate driving apparatus for extending or retracting said lower rack plate and said upper rack plate in the plate width direction.
In accordance with the above constitution, when the lower rack plate and the upper rack plate are retracted or extended in the plate width direction by the rack plate driving apparatus, the guide plates fixed to the rack plates are moved horizontally by the same distance in the width direction of the rolled plates by the action of the racks and the pinion. In the centering apparatuses, by setting the left and right guide plates to be at the same distance from the center line of the joining apparatus in the rolling direction, the left and right guide plates can be moved by the same distance from the center line of the joining apparatus in the rolling direction at all the time and therefore the center line of the rolled plate can be aligned with the center line of the joining apparatus in the rolling direction.
Further, preferably, said tailing end centering apparatus has elevating apparatuses and carries out a centering operation for aligning the center line of the rolled plate that is kept raised or lowered by said tailing end pinch rolls with the center line of the joining apparatus in the rolling direction.
According this constitution, the tailing end of the preceding rolled plate is raised higher than the leading end of the succeeding rolled plate by the tailing end pinch rollers and after one surface to be joined is machined and is lowered, one surface is joined to the other surface of the leading end of the succeeding rolled plate. The centering operation of the preceding rolled plate is carried out with the unmachined tailing end of the preceding rolled plate raised and after the center line of the rolled plate is aligned with the center line of the joining apparatus in the rolling direction, the machining is carried out and then the tailing end of the preceding rolled plate is lowered to join one surface of the tailing end of the preceding rolled plate to the other surface of the leading end of the succeeding rolled plate. At that time, the centering can be made again to align positively the center lines of the rolled plates. Since the tailing end centering apparatus has an elevating apparatus, the centering can be made twice in this manner.
To attain the second object, according to the present invention, there is provided a cutter cooling apparatus of a rolled plate joining apparatus for joining rolled plates after cutting the rolled plates by moving, horizontally in the width direction of the rolled plates, a cutter that is fitted to the extremity of a slant shaft and is rotated, wherein said cutter has a plurality of cutter tips (e.g., made of a cemented carbide produced by sintering WC (tungsten carbide), a major component, together with Co (cobalt)) on the surfaces and is abutted on and fixed to a flange section provided to said shaft by putting from the extremity of the shaft, a supply ring is fitted to form an annular space behind said flange section between it and the outer circumferential surface of said shaft, said shaft is provided with a supply passage passing through the inside of said shaft from said annular space to communicate with a contact surface of said flange section in contact with said cutter, said cutter is provided with cooling passages in communication with said supply passage and extending to said cutter tips, and a coolant is supplied from the outside into said annular space to cool said cutter tips from the inner surfaces.
In the above-described cutter cooling apparatus of a rolled plate joining apparatus, the cutter tips are brought in contact with a coolant (a cooling non-oxidizing liquid or cooling inert gas) not from the outside of the high-temperature atmosphere to which the cutter is exposed but from the inside. That is, the coolant can reach the inner surfaces (the surfaces where the connection is made) of the cutter tips through the supply passage and the cooling passages from the annular space of the supply ring. The coolant reached the inner surfaces of the cutter tips leaks outside from their gaps to form streams. Therefore, a fresh coolant can be supplied to the cutter tips all the time and therefore the cooling can be carried out efficiently.
Further, according to the present invention, there is provided a cutter cooling apparatus of a rolled plate joining apparatus for joining rolled plates after cutting the rolled plates by moving, horizontally in the width direction of the rolled plates, a cutter that is fitted to the extremity of a slant shaft and is rotated, wherein a cover having opening sections at positions corresponding to the position of said cutter is provided on one or each of the opposite sides of said shaft, a cooling pipe for supplying a coolant is supported outside of said cover, cooling nozzles directed to said opening sections from said cooling pipe are provided, and a coolant is jetted from said cooling nozzles to said cutter to cool said cutter.
The above-described present cutter cooling apparatus of a rolled plate joining apparatus jets a coolant (a cooling non-oxidizing liquid or cooling inert gas) from the outside of the cutter to carry out the cooling. That is, a cover that supports a cooling pipe and cooling nozzles and screens out a high-temperature atmosphere is provided and the coolant is jetted from the openings thereof to the surfaces of the cutter tips. Therefore, while the temperature of the coolant is kept low, it can be supplied to the cutter to effect the cooling efficiently.
Furthermore, according to the present invention, there is provided a cutter cooling apparatus of a rolled plate joining apparatus for joining rolled plates after cutting the rolled plates by moving, horizontally in the width direction of the rolled plates, a cutter that is fitted to the extremity of a slant shaft and is rotated, wherein said cutter has a plurality of cutter tips on the surfaces and is abutted on and fixed to a flange section provided to said shaft by putting from the extremity of the shaft, a supply ring is fitted to form an annular space behind said flange section between it and the outer circumferential surface of the shaft, said shaft is provided with a supply passage passing from said annular space through the inside of said shaft to communicate with a contact surface of said flange section in contact with said cutter, said cutter is provided with cooling passages in communication with said supply passage and extending to said cutter tips, a cover having opening sections at positions corresponding to the position of said cutter is provided on one or each of the opposite sides of said shaft, a cooling pipe for supplying a coolant is supported outside of said cover, a supply pipe for supplying a coolant from said cooling pipe into said annular space is connected to said supply ring, cooling nozzles directed to said opening sections from said cooling pipe are provided, and a coolant from said cooling passage is brought in contact with the inner surfaces of said cutter tips and is jetted from said cooling nozzles to said cutter tips to cool said cutter tips from the surfaces and the undersurfaces.
The above-described present cutter cooling apparatus of a rolled plate joining apparatus cools cutter tips from the surfaces and the undersurfaces thereof. That is, internal cooling by supplying a coolant (a cooling non-oxidizing liquid or cooling inert gas) to the inner surfaces of cutter tips through the supply ring (annular space), the supply passage, and the cooling passages through a cooling pipe and external cooling by jetting the coolant supplied from the cooling pipe to the surfaces of the cutter tips from cooling nozzles can be carried out simultaneously. Accordingly, the cutter (particularly the cutter tips) can be efficiently cooled.
To attain the third object, according to the present invention, there is provided a rolled plate joining apparatus for joining rolled plates by cutting one surface of the tailing end of a preceding rolled plate and the other surface of the leading end of a succeeding rolled plate while traveling in the width direction and by overlapping the resulting cut surfaces to be joined, comprising machining apparatuses each having a cutter for cutting one surface of the tailing end and the other surface of the leading end, a traversing apparatus for running said machining apparatuses in the plate width direction to move said machining apparatuses to waiting positions outside of the plate width, and cutter cooling apparatuses provided in said waiting positions for cooling said cutters.
By this constitution, the joining of rolled plates is carried out with an interval between the joining operations, after the cutting of the surfaces to be joined, the machining apparatus waits in the waiting position that is outside of the plate width, during that waiting the cutter is cooled by the cutter cooling apparatus, so that the increase in temperature during the cutting can be lowered and the life of the cutter tips can be prolonged.
Further, according to the present invention, there is provided a rolled plate joining apparatus for joining rolled plates by cutting one surface of the tailing end of a preceding rolled plate and the other surface of the leading end of a succeeding rolled plate while traveling in the width direction and by overlapping the resulting cut surfaces to be joined, comprising machining apparatuses each having a cutter for cutting one surface of the tailing end and the other surface of the leading end, a traversing apparatus for running said machining apparatuses in the plate width direction to move said machining apparatuses to waiting positions outside of the plate width, and applying apparatuses provided in said waiting positions for applying an abrasion preventive agent to said cutters.
By this constitution, the joining of rolled plates is carried out with an interval between the joining operations, after the cutting of the surfaces to be joined, the machining apparatus waits in the waiting position that is outside of the plate width, during that waiting an abrasion preventive agent can be applied to the cutter tips to reduce the abrasion of the cutter tips.
Further, according to the present invention, there is provided a rolled plate joining apparatus for joining rolled plates by cutting one surface of the tailing end of a preceding rolled plate and the other surface of the leading end of a succeeding rolled plate while traveling in the width direction and by overlapping the resulting cut surfaces to be joined, comprising machining apparatuses each having a cutter for cutting one surface of the tailing end and the other surface of the leading end, a traversing apparatus for running said machining apparatuses in the plate width direction to move said machining apparatuses to waiting positions outside of the plate width, and replacing apparatuses provided in said waiting positions for replacing said cutters, wherein at least two machining apparatuses wait in said waiting positions.
By this constitution, if the cutter is damaged during the cutting of the surfaced to be joined, the particular machining apparatus is moved to the waiting position and is replaced with the machining apparatus waiting in the waiting position, so that the joining operation can be resumed quickly. Further, at the waiting position, the cutter whose cutter tips have been damaged can be replaced.
To attain the fourth object, according to the present invention, there is provided a continuous hot rolling apparatus, comprising a sizing press for forcing down a rolled plate in the width direction supplied from a heating furnace to press the rolled plate to have a prescribed width, roughing mills for rolling said pressed rolled plate, a winding/unwinding machine for winding and unwinding the rolled plate rolled by said roughing mills, a crop shear for shearing the leading end and the tailing end of the rolled plate that has been unwound, an running joining machine that can travel at the conveying speed of the unwound rolled plate for joining the tailing end of the preceding rolled plate and the leading end of the succeeding rolled plate that have been sheared by said crop shear, a finishing mill for carrying out finish rolling of the joined rolled plates, a winding machine for winding the rolled plate that has been subjected to finish rolling, and a cutting machine positioned on the entrance side of said winding machine for cutting the rolled plate in accordance with the wound length.
By the above constitution, since the sizing press is forced down in the plate width by a press, the ability of adjusting the plate width is large, and therefore if the number of the types of the widths of the slabs is small, slabs having various widths can be made. Thus, by making the widths of slabs less varied, the operation of varying the width of the slab on the side of the continuous casting apparatus is made less often and therefore the productivity is improved. By providing the winding/unwinding machine after the roughing mills, the rough rolling line is shortened, and by winding the rolled plates into a coil, the effect of keeping temperature prevents the rolled plates to be supplied to the finishing mill from being cooled. The leading end and the tailing end of the rolled plates are severed by the crop shear suitably for joining and are then joined by the joining machine, and the strip after the finish rolling is suitably sheared by the shear on its exit side and is wound by the winding machines successively, so that the continuous rolling becomes possible to improve the productivity.
According to a preferred embodiment of the present invention, the above finishing mill comprises a plurality of finishing mills and an edge forming machine having vertical rolls provided on the opposite sides of the rolled plate is placed at at least one position out of positions on the entrance sides of said finishing mills.
By this constitution, a bulge at joined sections joined by the joining machine and edge drops are formed by the edge forming machine and therefore the precision of the plate width and the precision of the plate thickness can be improved. Further, since the edge forming machine carries out the forming by vertical rolls, members that are not used as proper products as in the case of a forming machine for cutting defective parts are not produced, and therefore the yield of the material is improved.
Further, the above running joining machine is preferably a reducing flame pressure welding type running joining machine wherein the tailing end of a preceding rolled plate and the leading end of a succeeding rolled plate are overlapped and the surfaces to be joined are pressure-welded with them covered with reducing flames.
By this constitution, since the surfaces to be joined are covered with reducing flames, the surfaces to be joined can be prevented from being oxidized and a good joined connection can be obtained. Since the joining is carried out by pressure welding, the joining can be carried out in a short period of time and the length along which the joining machine travels together with the rolled plates during the joining can be shortened. As a result, the rolling line is also shortened.
The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings.